Reading an eyeglasses prescription can seem intimidating, but it's actually quite straightforward once you understand what the different numbers and abbreviations mean. Here's a breakdown of the various components of a typical eyeglasses prescription:
OD and OS: These abbreviations stand for "oculus dexter" and "oculus sinister," which are Latin terms that mean "right eye" and "left eye," respectively.
Sphere (SPH): This number indicates the degree of nearsightedness or farsightedness in each eye, measured in diopters. A negative number (-) indicates nearsightedness, while a positive number (+) indicates farsightedness.
Cylinder (CYL): This number indicates the degree of astigmatism in each eye, measured in diopters. Astigmatism occurs when the cornea or lens of the eye is irregularly shaped, causing blurred vision at all distances. If you have no astigmatism, this section of your prescription will be left blank.
Axis: This number indicates the orientation of the astigmatism in each eye, measured in degrees from 1 to 180. If you have no astigmatism, this section of your prescription will be left blank.
Add: This number indicates the degree of additional magnifying power needed for reading or close work in bifocal or progressive lenses. If you do not require bifocals or progressive lenses, this section of your prescription will be left blank.
Pupillary Distance (PD): The pupillary distance (PD) is the distance between the center of one pupil to the center of the other pupil. This distance is important because it affects the way light enters the eyes and how it is focused. Correctly measuring the PD ensures that prescription eyewear is accurately centered over the eyes, allowing the eyes to focus properly.
Here's an example prescription:
OD: -2.00 -1.00 x 90 OS: -1.50 -0.75 x 180 Add: +2.00
This prescription indicates that the right eye (OD) has a sphere power of -2.00 diopters, a cylinder power of -1.00 diopters, and an axis of 90 degrees. The left eye (OS) has a sphere power of -1.50 diopters, a cylinder power of -0.75 diopters, and an axis of 180 degrees. The prescription also indicates that the patient needs an additional magnifying power of +2.00 diopters for reading or close work.
Keep in mind that this is just a general example, and your prescription may have additional details or variations. If you're unsure about any aspect of your prescription, don't hesitate to ask your eye doctor or optometrist for clarification. Remember, an eyeglasses prescription cannot be used to purchase contact lenses!